The present invention pertains to a network system, a network management method, and a network management device and particularly relates to a network system, a network management method, and a network management device that are suitable for use to set up paths in a large-scale network subject to high quality requirements.
Along with recent expansion of communication networks, there is an increasing expectation for packet transport technologies. In packet transport technologies, paths (through which packets pass) which are established between communication devices serving as nodes are explicitly determined and their communication conditions are periodically checked, thereby managing path management status. One of the packet transport technologies is a Multi-Protocol Label Switching-Transport Profile (MPLS-TP) as a technology that is now in process of international standardization. Communication devices that support MPLS use a label that is a fixed-length identifier as path selection information to select a path. Moreover, MPLS-TP is provided with various functions for maintenance and operation.
Meanwhile, it is required to set up paths rapidly using a packet transport technology, as networks become larger in scale. A technology for setting up paths in such a large-scale network is found in Japanese Patent Application Laid-Open No. 2015-156546. In a hierarchical path control system described in Japanese Patent Application Laid-Open No. 2015-156546, the following challenge is addressed: when resetting up paths in a large-scale network, shortening a total time required for path control (resetting up) which is composed of an algorithm calculation time and a path setup time, while ensuring a predetermined accuracy. According to this hierarchical path control system, a central control device determines a collective disconnection domain according to collective topology information that is transmitted from respective subordinate control devices and then generates combined topology information in which the collective topology information is combined with topology information after the collective disconnection is performed. Then, after making path calculations and calculating order in which to set up paths, the central control device transmits results of path calculations to the respective subordinate control devices according to the order in which to set up paths.
Moreover, another technology about path setup in a network is a technology described in Japanese Patent Application Laid-Open No. 2010-11039. In a network system described in Japanese Patent Application Laid-Open No. 2010-11039, the following challenge is addressed: in a communication network in which paths are created by label switching, when setting up a path, path setup is carried out, taking account of a path setup time taken at node devices on the path. A node device in this network system measures a path setup time required to set up a path and notifies another node device of the path setup time. Each node device, upon being notified of a path setup time measured at another node device, stores the notified path setup time and determines a path based on such path setup time.